Pinpoint Test I: DTC C1991 - Module Calibration Failure

WARNING: This page is about a different car, the 2007 Lincoln MKX and 2007 Ford Edge. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: The RSC warning indicator flashes when a system calibration is required. Calibration is required after certain DTCs are cleared.

NOTE: Make sure the vehicle is not on a hoist and is sitting on level ground before carrying out ABS module calibration.

I1 CHECK FOR DTCs
- Connect the diagnostic tool.
- Key in ON position.
- Retrieve and record any ABS module DTCs.
- Are any other DTCs retrieved along with C1991?
1. YES : Go to the ABS DTC Chart.
  Some of the pinpoint tests recommend ABS module calibration prior to any further diagnostics. In this case, go to I2.
2. NO : Go to I2.
I2 CALIBRATE THE ABS MODULE
- Carry out the ABS module calibration per the scan tool instructions.
- Does the calibration complete for all of the roll stability control sensors, and does the stability control active/fail lamp stop flashing and turn off?
1. YES : Go to I3.
2. NO : Go to I4.
  Some concerns cause the calibration not to complete. If sent here from another pinpoint test, return to that pinpoint test for further diagnostics.
I3 CLEAR DTC C1991
- Using the scan tool, clear the DTC.
- Does the DTC clear?
1. YES : TEST DRIVE the vehicle above 32 km/h (20 mph) and CARRY OUT at least one ABS stop. REPEAT the self-test.
  If sent here from another pinpoint test, return to that pinpoint test for further diagnostics.
2. NO : Go to I4.
I4 MONITOR THE STEERING WHEEL ROTATION SENSOR PID
- Key in ON position.
- Using the scan tool, monitor the ABS module SWA POS PID while rotating the steering wheel clockwise and counterclockwise very slowly.
- Does the PID move in intervals of 1 degree?
1. YES : Go to Pinpoint Test F .
2. NO : Go to Pinpoint Test E .